In order to achieve objectives such as handover, exchange of information between evolved NodeBs (eNBs), and management, a system needs to configure a neighbouring cell list for each cell, but in a configured neighbouring cell list, a neighbouring cell may be missing.
A neighbouring cell is missing for many reasons: Some are predictable, for example, a new cell is added, or the original frequency, scrambling code, or any other attribute of a cell changes but a neighbouring cell relation of the cell is not updated in time; some are beyond control of an operator, for example, dismantling a building results in a new change of signal coverage of a cell, but the neighbouring cell relation of the cell is not updated in time; and some are missing because network planning personnel fail to correctly configure the neighbouring cell relation of a cell, and so on. The missing configuration of a neighbouring cell may cause a user equipment (UE) to fail to hand over to another cell in time, which overloads the current cell, degrades signal quality and increases interference of the current cell, or results in a call drop of a user.
Previously, after detecting a new cell, an operator and network planning personnel decide, according to a certain strategy, whether or not to manually add a neighbouring cell relation for the current cell.
A long term evolution (LTE) system adds a neighbouring cell list by using an ANR function.
The ANR function includes: A UE assists in measuring a new cell and reports measured information to an eNB, and the eNB implements a function of adding a neighbouring cell list, so that a neighbouring cell is automatically added by the system and does not need to be manually added.
Currently, a measurement and reporting process performed by a UE in the ANR is: The UE reports to an eNB a measured physical cell identifier (PCI) of a cell around, and the eNB checks cell information relating to the PCI. If the PCI is a new PCI, the eNB considers that a new cell is found. If the eNB decides to add this new cell (of course, the eNB may also decide not to add this new cell), the eNB notifies the UE again to further measure a cell global ID (CGI). If the UE completes the measurement, the UE reports some relevant information of the cell such as the CGI to the eNB.
At some cell edges, when a radio link failure (RLF) occurs suddenly, the UE reselects a cell and sends a radio resource control (RRC) reestablishment request to the new cell. If there is no UE context in the new cell, the eNB of the new cell sends an RRC reestablishment failure message to the UE, and the UE goes into an idle state. In order to keep a service uninterrupted, the UE may trigger an RRC link establishment process or trigger a tracking area update (TAU) process by a non access stratum (NAS).
In the process of implementing the present invention, the inventor discovers that the prior art has at least the following problems:
When an RLF occurs, the ANR function cannot be completed, and instead, a separate ANR measurement is required, which wastes measurement time and affects network performance.